Problems with noise transmission from one floor to another within apartment buildings or other multi-tenant buildings are often quite severe. Good building design dictates that the floors and walls of individual units in the building be reasonably soundproof. Particularly, the floors of such building units should resist the transmission not only of airborne sounds such as music or speech, but also impact-produced sounds from walking, dancing and the like.
Sound insulating flooring which previously has been employed is generally either difficult to install, yields poor sound insulating qualities, or is expensive. In one instance, for example, floors have been prepared from a mixture of Portland cement and sand, the mixture being troweled on a suitable substrate and finished to provide a smooth surface. Shrinkage effects during setting of this floor can result in floor cracks, and the troweling and finishing procedure is time consuming and hence expensive. Another instance involves the use of preformed sheets of particle board or of gypsum-type Sheetrock. Again, the installation procedure is time consuming, and a considerable wastage of material results.
In commonly owned Jorgenson, et al U.S. Pat. No. 4,075,374 issued Feb. 21, 1978, a flooring composition was described as comprising a slurry which included pressure-calcined calcium sulfate hemihydrate, sand, a polymeric latex, an antifoam agent, and sufficient water to provide the slurry with a water-like consistency. This flooring preparation has given good results over a period of years; problems, however, have been encountered in regulating the setting or curing time of the preparation. Further, the sand which is employed in that preparation tends to settle slowly during the curing stage, resulting in a flooring which is quite rich in sand at its lower surface and which is quite poor in sand and rich in latex at its upper surface. Perhaps because of expansion effects during the curing cycle, a number of floors which have been poured using this preparation have tended to crack or chip during subsequent construction activities, thereby requiring workmen to return to the job site to correct the problem. Depending upon the particular economics of each situation, the requirement of having workmen return to the job site can transform a profit making venture into a financial loss, notwithstanding the fact that acoustic floors can be more economically produced in accordance with the invention set out in said U.S. Pat. No. 4,075,374 than by any method prior thereto.
It would be highly desirable to provide a watery, runny flooring preparation which, during the curing cycle, would exhibit minimum expansion and substantially no settling of the sand therein, and which would permit a floor to be prepared in a manner requiring no return visits by workman to repair defects.